4 ms·

But POWER isn't a proprietary isa anymore? https://www.servethehome.com/ibm-open-sources-power-isa-and-aligns-openpower-to-linux-foundation/ https://www.servet

But POWER isn't a proprietary isa anymore? https://www.servethehome.com/ibm-open-sources-power-isa-and-aligns-openpower-to-linux-foundation/ https://www.servethehome.com/ibm-open-sources-power-isa-and-...

gridlockd 7y ago
Oh yeah, I guess I remember hearing about that now. Well, in that case I don't like it because IBM made it. Also it's old. It's not coming back. RISC-V is new and sexy.
- dragontamer 7y ago
  > Also it's old. It's not coming back. The #1 Supercomputer in the world is using POWER9: Summit. Granted, its mostly because OpenCAPI allows for POWER9 + NVidia GPUs to interface at extremely high speeds, but a win is a win in my books. https://www.olcf.ornl.gov/summit/ https://www.olcf.ornl.gov/summit/ PowerPC has silly things like decimal-floats support and quad-precision support. I mean, they exist for emulating old COBOL code for the most part, but decimal-floats solve the age-old problem of how to represent financial data with floating-point, and with perfect accuracy at that. There's certainly good and unique ideas in the PowerPC ISA.
  - ajdlinux 7y ago
    Minor correction: Nvidia GPUs on POWER9 are connected using NVLink, which shares its physical layer with OpenCAPI, and like OpenCAPI is cache-coherent, etc, but uses a different data link and transport layer protocol. (I'm one of the OpenCAPI Linux kernel driver maintainers)
- pgeorgi 7y ago
  > RISC-V is new and sexy. RISC-V is pretty shoddy (M mode, a separate hypervisor mode instead of proper orthogonality, CSRs), but that's exactly what I'd expect from thesis-driven development (remember that RISC-V was an academic project for a long time). Holding their feet to the fire so that they undo some of that damage seems to be a pretty good idea to me, and if it's PowerPC what it takes to do that, that's not the worst choice IMHO.
  - gridlockd 7y ago
    I'm sure your technical arguments are well-reasoned, but I'm not changing my mind. I already made a modest emotional investment into RISC-V.
  - monocasa 7y ago
    M mode isn't a hypervisor mode. It's more like x86 System Management Mode, or ARM's EL3. Hypervisor was originally going to be a separate H mode, but they made it orthongonal with S mode instead as a sort of bank switch. And if CSRs are bad, then POWER's SPRs are bad; they're basically the same thing except POWER makes much less effort to be consistent or introspectable. POWER is way more braindead in it's supervisor state. For instance they finally gave you a sane radix tree page table with POWER9, but now you can't address all the virtual address space you could before, which, yes, is its own problem for some systems.
    - pgeorgi 7y ago
      > M mode isn't a hypervisor mode. I'm well aware. I should have used a semicolon. I take issue with both m mode and hypervisor mode.
      - monocasa 7y ago
        What do you take issue with M mode? And they removed H mode.
        pgeorgi 7y ago
        > What do you take issue with M mode? As you say, it's similar to x86's SMM, and like all firmware stuff that survives beyond the kernel entry point, is something that I don't trust, and where experience tells me that it's a venue for vendors to mess things up. One of the hardest issues with real time computing on x86 is... SMM. One of the easiest ways to bypass security on x86 is... SMM. The workaround for "securing" SMM is to sprinkle virtualization on it (STM: because more virtualization is always better), which only adds more complexity (and messes up real time computing even more). And all that closed source because SoC/firmware vendors quickly and happily assume that such modes are owned by them, to the detriment of whoever wants to know what their machine is doing. Not having such a mode helps keep vendors honest: if there's a need for a workaround, document it and kernel developers can implement it (and they will). None of that "install this firmware update that we don't tell you anything about in order to hopefully be slightly more secure than yesterday" crap. > And they removed H mode. Well, that's an improvement. Thanks for making me look it up again. One down, one to go.
- ksec 7y ago
  In case Mr 7 months' old account are wondering why you are downvoted, may I remind you this is HN, and not reddit.
  - gridlockd 7y ago
    > In case Mr 7 months' old account are wondering why you are downvoted, may I remind you this is HN, and not reddit. Why would I care? These votes are worthless. I keep noticing that people here are looking down on Reddit, as if HN was even comparable to Reddit. Lots of subreddits are high quality, lots of subreddits are junk. HN would be somewhere in the middle.

gridlockd 7y ago

Oh yeah, I guess I remember hearing about that now. Well, in that case I don't like it because IBM made it. Also it's old. It's not coming back. RISC-V is new and sexy.

dragontamer 7y ago
> Also it's old. It's not coming back. The #1 Supercomputer in the world is using POWER9: Summit. Granted, its mostly because OpenCAPI allows for POWER9 + NVidia GPUs to interface at extremely high speeds, but a win is a win in my books. https://www.olcf.ornl.gov/summit/ https://www.olcf.ornl.gov/summit/ PowerPC has silly things like decimal-floats support and quad-precision support. I mean, they exist for emulating old COBOL code for the most part, but decimal-floats solve the age-old problem of how to represent financial data with floating-point, and with perfect accuracy at that. There's certainly good and unique ideas in the PowerPC ISA.
- ajdlinux 7y ago
  Minor correction: Nvidia GPUs on POWER9 are connected using NVLink, which shares its physical layer with OpenCAPI, and like OpenCAPI is cache-coherent, etc, but uses a different data link and transport layer protocol. (I'm one of the OpenCAPI Linux kernel driver maintainers)
pgeorgi 7y ago
> RISC-V is new and sexy. RISC-V is pretty shoddy (M mode, a separate hypervisor mode instead of proper orthogonality, CSRs), but that's exactly what I'd expect from thesis-driven development (remember that RISC-V was an academic project for a long time). Holding their feet to the fire so that they undo some of that damage seems to be a pretty good idea to me, and if it's PowerPC what it takes to do that, that's not the worst choice IMHO.
- gridlockd 7y ago
  I'm sure your technical arguments are well-reasoned, but I'm not changing my mind. I already made a modest emotional investment into RISC-V.
- monocasa 7y ago
  M mode isn't a hypervisor mode. It's more like x86 System Management Mode, or ARM's EL3. Hypervisor was originally going to be a separate H mode, but they made it orthongonal with S mode instead as a sort of bank switch. And if CSRs are bad, then POWER's SPRs are bad; they're basically the same thing except POWER makes much less effort to be consistent or introspectable. POWER is way more braindead in it's supervisor state. For instance they finally gave you a sane radix tree page table with POWER9, but now you can't address all the virtual address space you could before, which, yes, is its own problem for some systems.
  - pgeorgi 7y ago
    > M mode isn't a hypervisor mode. I'm well aware. I should have used a semicolon. I take issue with both m mode and hypervisor mode.
    - monocasa 7y ago
      What do you take issue with M mode? And they removed H mode.
      - pgeorgi 7y ago
        > What do you take issue with M mode? As you say, it's similar to x86's SMM, and like all firmware stuff that survives beyond the kernel entry point, is something that I don't trust, and where experience tells me that it's a venue for vendors to mess things up. One of the hardest issues with real time computing on x86 is... SMM. One of the easiest ways to bypass security on x86 is... SMM. The workaround for "securing" SMM is to sprinkle virtualization on it (STM: because more virtualization is always better), which only adds more complexity (and messes up real time computing even more). And all that closed source because SoC/firmware vendors quickly and happily assume that such modes are owned by them, to the detriment of whoever wants to know what their machine is doing. Not having such a mode helps keep vendors honest: if there's a need for a workaround, document it and kernel developers can implement it (and they will). None of that "install this firmware update that we don't tell you anything about in order to hopefully be slightly more secure than yesterday" crap. > And they removed H mode. Well, that's an improvement. Thanks for making me look it up again. One down, one to go.
ksec 7y ago
In case Mr 7 months' old account are wondering why you are downvoted, may I remind you this is HN, and not reddit.
- gridlockd 7y ago
  > In case Mr 7 months' old account are wondering why you are downvoted, may I remind you this is HN, and not reddit. Why would I care? These votes are worthless. I keep noticing that people here are looking down on Reddit, as if HN was even comparable to Reddit. Lots of subreddits are high quality, lots of subreddits are junk. HN would be somewhere in the middle.